Free-Position Wireless Charger Keep-Out

ABSTRACT

Systems, methods and apparatus for wireless charging are disclosed. One method for operating a charging device includes determining that a chargeable device is positioned proximate to a charging coil provided by a charging surface, providing a charging current to the charging coil, and excluding adjacent coils from operation while the current is provided to the charging coil. Each of the adjacent coils is located within the charging surface adjacent to the charging coil. The adjacent coils may be excluded from participating in one or more device discovery procedures. The charging device may refrain from providing charging current to the adjacent coils while the current is provided to the charging coil.

PRIORITY CLAIM

This application claims priority to and the benefit of provisional patent application No. 62/938,308 filed in the United States Patent Office on Nov. 20, 2019 and of provisional patent application No. 63/066,315 filed in the United States Patent Office on Aug. 16, 2020, the entire content of these applications being incorporated herein by reference as if fully set forth below in their entirety and for all applicable purposes.

TECHNICAL FIELD

The present invention relates generally to wireless charging of batteries, including batteries in mobile computing devices and more particularly to preventing interference from pings used by a wireless charging device to locate a first device while the wireless charging device is actively charging a second device.

BACKGROUND

Wireless charging systems have been deployed to enable certain types of devices to charge internal batteries without the use of a physical charging connection. Devices that can take advantage of wireless charging include mobile processing devices and mobile communication devices. Standards, such as the Qi standard defined by the Wireless Power Consortium enable devices manufactured by a first supplier to be wirelessly charged using a charger manufactured by a second supplier. Standards for wireless charging are optimized for relatively simple configurations of devices and tend to provide basic charging capabilities.

Conventional wireless charging systems typically use a “Ping” or “digital ping” to determine if a receiving device is present on or proximate to a transmitting coil in a base station for wireless charging. The transmitter coil has an inductance (L) and a resonant capacitor that has a capacitance (C) that is coupled to the transmitting coil to obtain a resonant LC circuit. A Ping is produced by delivering power to the resonant LC circuit. Power is applied for a duration of time (90 ms in one example) while the transmitter listens for a response from a receiving device. The response may be provided in a signal encoded using Amplitude Shift Key (ASK) modulation. This conventional Ping-based approach can be slow due to the 90 ms duration, and can dissipate large and significant amount of energy, which may amount to 80 mJ per Ping.

In one example, a typical transmitting base station may ping as fast as 12.5 times a second (period=1/80 ms) with a power consumption of (80 mJ*12.5) per second=1 W. In practice, most designs trade off responsiveness for a lower quiescent power draw by lowering the ping rate. As an example, a transmitter may ping 5 times a second with a resultant power draw of 400 mW.

A base station that has a single transmitting coil ceases Ping-based discovery when a chargeable device has an established presence and is receiving power through the transmitting coil. However, a multi-coil free position charging pad may continue Ping-based discovery after one or more chargeable devices are established on the charging pad and receiving power through different charging cells or transmitting coils. A Ping transmitted through a first transmitting coil to a newly discovered device, or to a device in motion, may interfere with a nearby device that is already receiving power form a second transmitting coil of the charging pad. For example, flux from the first transmitting coil can couple with the second transmitting coil or with the receiving coil in the already-established chargeable device. This coupling can disrupt communication with the already-established chargeable device and change the power transferred to the already-established chargeable device.

Improvements in wireless charging capabilities are required to support continually increasing complexity of multi-coil free position charging pads and their operating conditions.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a charging cell that may be provided on a charging surface in accordance with certain aspects disclosed herein.

FIG. 2 illustrates an example of an arrangement of charging cells provided on a single layer of a segment of a charging surface that may be adapted in accordance with certain aspects disclosed herein.

FIG. 3 illustrates an example of an arrangement of charging cells when multiple layers are overlaid within a segment of a charging surface that may be adapted in accordance with certain aspects disclosed herein.

FIG. 4 illustrates the arrangement of power transfer areas provided on a charging surface by a charging device that employs multiple layers of charging cells configured in accordance with certain aspects disclosed herein.

FIG. 5 illustrates a wireless transmitter that may be provided in a charger base station in accordance with certain aspects disclosed herein.

FIG. 6 illustrates a first example of a response to a passive ping in accordance with certain aspects disclosed herein.

FIG. 7 illustrates a second example of a response to a passive ping in accordance with certain aspects disclosed herein.

FIG. 8 illustrates examples of observed differences in responses to a passive ping in accordance with certain aspects disclosed herein.

FIG. 9 is a flowchart that illustrates a power transfer management procedure that may be employed by a wireless charging device implemented in accordance with certain aspects disclosed herein.

FIG. 10 illustrates a topology that supports direct current drive in a wireless charger adapted in accordance with certain aspects disclosed herein.

FIG. 11 illustrates certain charging configurations for a chargeable device located on a surface of a charging device provided in accordance with certain aspects disclosed herein.

FIG. 12 illustrates coils disabled by certain charging configurations for a chargeable device located on a surface of a charging device provided in accordance with certain aspects disclosed herein.

FIG. 13 is flowchart illustrating an example of a method for detecting an object performed by a controller provided in a wireless charging apparatus adapted in accordance with certain aspects disclosed herein.

FIG. 14 illustrates one example of an apparatus employing a processing circuit that may be adapted according to certain aspects disclosed herein.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of wireless charging systems will now be presented with reference to various apparatus and methods. These apparatus and methods will be described in the following detailed description and illustrated in the accompanying drawing by various blocks, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

By way of example, an element, or any portion of an element, or any combination of elements may be implemented with a “processing system” that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a processor-readable storage medium. A processor-readable storage medium, which may also be referred to herein as a computer-readable medium may include, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disk (CD), digital versatile disk (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), Near Field Communications (NFC) token, random access memory (RAM), read only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, a removable disk, a carrier wave, a transmission line, and any other suitable medium for storing or transmitting software. The computer-readable medium may be resident in the processing system, external to the processing system, or distributed across multiple entities including the processing system.

Computer-readable medium may be embodied in a computer-program product. By way of example, a computer-program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

Overview

Certain aspects of the present disclosure relate to systems, apparatus and methods applicable to wireless charging devices and techniques. In a wireless charging device, charging cells may be configured with one or more inductive coils to provide a charging surface that can charge one or more devices wirelessly. The location of a device to be charged may be detected through sensing techniques that associate location of the device to changes in a physical characteristic centered at a known location on the charging surface. Sensing of location may be implemented using capacitive, resistive, inductive, touch, pressure, load, strain, and/or another appropriate type of sensing.

In one aspect of the disclosure, an apparatus has a battery charging power source, a plurality of charging cells configured in a matrix. Each charging cell in the plurality of charging cells may include one or more coils surrounding a power transfer area. The plurality of charging cells may be arranged adjacent to a charging surface without overlap of power transfer areas of the charging cells in the plurality of charging cells.

Certain aspects of the present disclosure relate to systems, apparatus and methods for wireless charging using stacked coils that can charge target devices presented to a charging device without a requirement to match a particular geometry or location within a charging surface of the charging device. Each coil may have a shape that is substantially polygonal. In one example, each coil may have a hexagonal shape. Each coil may be implemented using wires, printed circuit board traces and/or other connectors that are provided in a spiral. Each coil may span two or more layers separated by an insulator or substrate such that coils in different layers are centered around a common axis.

According to certain aspects disclosed herein, power can be wirelessly transferred to a receiving device located anywhere on a charging surface, which can have an arbitrarily defined size and/or shape without regard to any discrete placement locations enabled for charging. Multiple devices can be simultaneously charged on a single charging surface. The charging surface may be manufactured using printed circuit board technology, at low cost and/or with a compact design.

One aspect of the present disclosure relates to systems, apparatus and methods that prevent or restrict interference caused by digital pings. A digital ping may also be referred to as an “active ping” and may be transmitted in accordance with a protocol or standard. A digital ping may be transmitted from a charging cell with a power level sufficient to cause coupling of electromagnetic flux with a neighboring or nearby charging cell. In one example, interference may be caused when electromagnetic flux transmitted as part of the digital ping is coupled with a power transmitting coil that is actively transmitting power through a charging surface of a wireless charging device. In another example, interference may be caused when electromagnetic flux transmitted as part of the digital ping is coupled with a power receiving coil in a device that is receiving power through the charging surface of the wireless charging device. Interference can be avoided by excluding charging cells located near an actively transmitting charging cell from participation in device discovery procedures.

In one aspect of this disclosure, a wireless charging device may be configured to determine that a chargeable device is positioned proximate to a charging coil provided by a charging surface, provide a charging current to the charging coil and exclude a plurality of adjacent coils from operation while the current is provided to the charging coil. Each of the adjacent coils is located within the charging surface adjacent to the charging coil. Adjacent coils may be excluded from operation by excluding the plurality of adjacent coils from participating in one or more device discovery procedures, including digital pings. Adjacent coils may be excluded from operation by excluding the plurality of adjacent coils from participating in charging a different chargeable device.

Charging Cells

According to certain aspects disclosed herein, a charging device may provide a charging surface using charging cells that are deployed adjacent to the charging surface. In one example, the charging cells are deployed in one or more layers of the charging surface in accordance with a honeycomb packaging configuration. A charging cell may be implemented using one or more coils that can each induce a magnetic field along an axis that is substantially orthogonal to the charging surface adjacent to the coil. In this description, a charging cell may refer to an element having one or more coils where each coil is configured to produce an electromagnetic field that is additive with respect to the fields produced by other coils in the charging cell, and directed along or proximate to a common axis.

In some implementations, a charging cell includes coils that are stacked along a common axis and/or that overlap such that they contribute to an induced magnetic field substantially orthogonal to the charging surface. In some implementations, a charging cell includes coils that are arranged within a defined portion of the charging surface and that contribute to an induced magnetic field within the substantially orthogonal portion of the charging surface associated with the charging cell. In some implementations, charging cells may be configurable by providing an activating current to coils that are included in a dynamically-defined charging cell. For example, a charging device may include multiple stacks of coils deployed across the charging surface, and the charging device may detect the location of a device to be charged and may select some combination of stacks of coils to provide a charging cell adjacent to the device to be charged. In some instances, a charging cell may include, or be characterized as a single coil. However, it should be appreciated that a charging cell may include multiple stacked coils and/or multiple adjacent coils or stacks of coils. The coils may be referred to herein as charging coils, wireless charging coils, transmitter coils, transmitting coils, power transmitting coils, power transmitter coils, or the like.

FIG. 1 illustrates an example of a charging cell 100 that may be deployed and/or configured to provide a charging surface of a charging device. As described herein, the charging surface may include an array of charging cells 100 provided on one or more substrates 106. A circuit comprising one or more integrated circuits (ICs) and/or discrete electronic components may be provided on one or more of the substrates 106. The circuit may include drivers and switches used to control currents provided to coils used to transmit power to a receiving device. The circuit may be configured as a processing circuit that includes one or more processors and/or one or more controllers that can be configured to perform certain functions disclosed herein. In some instances, some or all of the processing circuit may be provided external to the charging device. In some instances, a power supply may be coupled to the charging device.

The charging cell 100 may be provided in close proximity to an outer surface area of the charging device, upon which one or more devices can be placed for charging. The charging device may include multiple instances of the charging cell 100. In one example, the charging cell 100 has a substantially hexagonal shape that encloses one or more coils 102, which may be constructed using conductors, wires or circuit board traces that can receive a current sufficient to produce an electromagnetic field in a power transfer area 104. In various implementations, some coils 102 may have a shape that is substantially polygonal, including the hexagonal charging cell 100 illustrated in FIG. 1. Other implementations provide coils 102 that have other shapes. The shape of the coils 102 may be determined at least in part by the capabilities or limitations of fabrication technology, and/or to optimize layout of the charging cells on a substrate 106 such as a printed circuit board substrate. Each coil 102 may be implemented using wires, printed circuit board traces and/or other connectors in a spiral configuration. Each charging cell 100 may span two or more layers separated by an insulator or substrate 106 such that coils 102 in different layers are centered around a common axis 108.

FIG. 2 illustrates an example of an arrangement 200 of charging cells 202 provided on a single layer of a segment of a charging surface of a charging device that may be adapted in accordance with certain aspects disclosed herein. The charging cells 202 are arranged according to a honeycomb packaging configuration. In this example, the charging cells 202 are arranged end-to-end without overlap. This arrangement can be provided without through-hole or wire interconnects. Other arrangements are possible, including arrangements in which some portion of the charging cells 202 overlap. For example, wires of two or more coils may be interleaved to some extent.

FIG. 3 illustrates an example of an arrangement of charging cells from two perspectives 300, 310 when multiple layers are overlaid within a segment of a charging surface that may be adapted in accordance with certain aspects disclosed herein. Layers of charging cells 302, 304, 306, 308 are provided within a segment of a charging surface. The charging cells within each layer of charging cells 302, 304, 306, 308 are arranged according to a honeycomb packaging configuration. In one example, the layers of charging cells 302, 304, 306, 308 may be formed on a printed circuit board that has four or more layers. The arrangement of charging cells 100 can be selected to provide complete coverage of a designated charging area that is adjacent to the illustrated segment.

FIG. 4 illustrates the arrangement of power transfer areas provided in a charging surface 400 that employs multiple layers of charging cells configured in accordance with certain aspects disclosed herein. The illustrated charging surface is constructed from four layers of charging cells 402, 404, 406, 408, which may correspond to the layers of charging cells 302, 304, 306, 308 in FIG. 3. In FIG. 4, each power transfer area provided by a charging cell in the first layer of charging cells 402 is marked “L1”, each power transfer area provided by a charging cell in the second layer of charging cells 404 is marked “L2”, each power transfer area provided by a charging cell in the third layer of charging cells 406 is marked “L3”, and each power transfer area provided by a charging cell in the fourth layer of charging cells 408 is marked “L4”.

Locating Devices on a Charging Surface

In accordance with certain aspects disclosed herein, location sensing may rely on changes in some property of the electrical conductors that form coils in a charging cell. Measurable differences in properties of the electrical conductors may include capacitance, resistance, inductance and/or temperature. In some examples, loading of the charging surface can affect the measurable resistance of a coil located near the point of loading. In some implementations, sensors may be provided to enable location sensing through detection of changes in touch, pressure, load and/or strain.

Certain aspects disclosed herein provide apparatus and methods that can sense the location of devices that are freely positioned on a charging surface. Location sensing may be accomplished using low-power differential capacitive sense techniques that can detect changes in capacitance of a coil in a charging cell. Differential capacitive sense can be used to determine location by first connecting two adjacent coils to the capacitive sense circuitry. Using these two coils the circuitry measures the capacitance through the use of one or more known methods. A first method includes applying a constant current waveform and calculating capacitance based on changes in voltage sensed by a measuring circuit. Calculation of capacitance can be based on the following equations:

Q=C*V,

Q=I*t.

If a known charge is delivered (Q) by sourcing a known constant current (I) for a specified amount of time (t), measurements of the voltage (V) can be used to calculate the capacitance (C). Measured capacitance can be compared to the last recorded measured value. Certain changes in capacitance are significant enough to indicate that the system has changed, enabling detection that something has become part of the system (e.g., a chargeable wireless telephone).

Changes in capacitance can be measured through the use of an RC time constant. A constantly varying square wave signal can be applied across a known resistance (R) and the unknown capacitance (C or Cx). The time to charge/discharge can them be measured using a timer and comparator. By using the time constant equation, capacitance can be calculated.

When a search identifies a potential device placement on the charging surface, the charging device may begin a ping procedure to identify a charging cell, a combination of charging cells and/or a combination of coils that are to be activated to charge the device placed on the charging surface. The ping procedure verifies that the device to be charged is compatible with the charging device and may identify a signal strength indicating whether the coils used to transmit the ping are best positioned for the requested or desired charging procedure.

Significant power savings can be achieved when a search is conducted to locate a device placed on or near in a multi-coil, free position charging pad before using pings to establish that the device is configured to receive charge from a wireless charging device. The savings in power consumption can be obtained by refraining from providing pings until a device is detected in a search, and by limiting ping transmissions to transmitting coils that are placed in proximity to the detected device and likely to be capable of establishing an electromagnetic charging connection with the detected device.

Wireless charging devices may be adapted in accordance with certain aspects disclosed herein to support a low-power discovery technique that can replace and/or supplement conventional ping transmissions. A conventional ping is produced by driving a resonant LC circuit that includes a transmitting coil of a base station. The base station then waits for an ASK-modulated response from the receiving device. The receiving device may modulate the current or voltage in a resonant circuit by modifying a reactive component in accordance with a signal to be modulated.

A low-power discovery technique may include utilizing a passive ping to provide fast and/or low-power discovery. According to certain aspects, a passive ping may be produced by driving a network that includes the resonant LC circuit with a fast pulse that includes a small amount of energy. The fast pulse excites the resonant LC circuit and causes the network to oscillate at its natural resonant frequency until the injected energy decays and is dissipated. In one example, the fast pulse may have a duration corresponding to a half cycle of the resonant frequency of the network and/or the resonant LC circuit. When the base station is configured for wireless transmission of power within the frequency range 100 kHz to 200 kHz, the fast pulse may have a duration that is less than 2.5 μs. In other examples, the fast pulse may have a duration corresponding to multiple cycles of the resonant frequency of the network and/or the resonant LC circuit.

The passive ping may be characterized and/or configured based on the natural frequency at which the network including the resonant LC circuit rings, and the rate of decay of energy in the network. The ringing frequency of the network and/or resonant LC circuit may be defined as:

$\begin{matrix} {\omega = \frac{1}{\sqrt{LC}}} & \left( {{Eq}.\; 1} \right) \end{matrix}$

The rate of decay is controlled by the quality factor (Q factor) of the oscillator network, as defined by:

$\begin{matrix} {Q = {\frac{1}{R}\sqrt{\frac{L}{C}}}} & \left( {{Eq}.\mspace{14mu} 2} \right) \end{matrix}$

Equations 1 and 2 show that resonant frequency is affected by L and C, while the Q factor is affected by L, C and R. In a base station provided in accordance with certain aspects disclosed herein, the wireless driver can have a fixed value of C as determined by the selection of the resonant capacitor. The values of L and R are determined by the wireless transmitting coil and by an object or device placed adjacent to the wireless transmitting coil.

The wireless transmitting coil is configured to be magnetically coupled with a receiving coil in a device to be charged that is placed within close proximity of the transmitting coil, and to couple some of its energy into the device to be charged. The L and R values of the transmitter circuit can be affected by the characteristics of the device to be charged, and/or other objects within close proximity of the transmitting coil. As an example, if a piece of ferrous material with a high magnetic permeability placed near the transmitter coils can increase the total inductance (L) of the transmitter coil, resulting in a lower resonant frequency, as shown by Equation 1. Some energy may be lost through heating of materials due to eddy current induction, and these losses may be characterized as an increase in the value of R thereby lowering the Q factor, as shown by Equation 2.

A wireless receiver placed in close proximity to the transmitter coil can also affect the Q factor and resonant frequency. The receiver may include a tuned LC network with a high Q which can result in the transmitter coil having a lower Q factor. The resonant frequency of the transmitter coil may be reduced due to the addition of the magnetic material in the receiver, which is now part of the total magnetic system. Table 1 illustrates certain effects attributable to different types of objects placed within close proximity to the transmitter coil.

TABLE 1 Object L R Q Frequency None present Base Value Base value Base Value (High) Base Value Ferrous Small Increase Large Increase Large Decrease Small Decrease Non-ferrous Small Decrease Large Increase Large Decrease Small Increase Wireless Receiver Large Increase Small Decrease Small Decrease Large Decrease

FIG. 5 illustrates a wireless transmitter 500 that may be provided in a charger base station. A controller 502 may receive a feedback signal that is filtered or otherwise processed by a conditioning circuit 508. The controller may control the operation of a driver circuit 504 that provides an alternating current to a resonant circuit 506 that includes a capacitor 512 and inductor 514. The resonant circuit 506 may also be referred to herein as a tank circuit, LC tank circuit, or LC tank, and the voltage 516 measured at an LC node 510 of the resonant circuit 506 may be referred to as the tank voltage.

The wireless transmitter 500 may be used by a charging device to determine if a compatible device has been placed on a charging surface. For example, the charging device may determine that a compatible device has been placed on the charging surface by sending an intermittent test signal (active ping or digital ping) through the wireless transmitter 500, where the resonant circuit 506 may detect or receive encoded signals when a compatible device responds to the test signal or modifies a characteristic of the test signal. In some examples, the charging device may be configured to activate one or more coils in at least one charging cell after receiving a response signal defined by standard, convention, manufacturer or application. In some examples, the compatible device can respond to a ping by communicating received signal strength such that the charging device can find an optimal charging cell to be used for charging the compatible device.

Passive ping techniques may use the voltage or current measured or observed at the LC node 510 to identify the presence of a receiving coil in proximity to the charging pad of a device adapted in accordance with certain aspects disclosed herein. In many conventional wireless charger transmitters, circuits are provided to measure voltage at the LC node 510 or to measure the current in the LC network. These voltages and currents may be monitored for power regulation purposes or to support communication between devices. In the example illustrated in FIG. 5, voltage at the LC node 510 is monitored, although it is contemplated that current may additionally or alternatively be monitored to support passive ping in which a short pulse is provided to the resonant circuit 506. A response of the resonant circuit 506 to a passive ping (initial voltage V0) may be represented by the voltage (VLC) at the LC node 510, such that:

$\begin{matrix} {V_{LC} = {V_{0}e^{- {(\frac{\omega}{2Q})}^{t}}}} & \left( {{Eq}.\mspace{14mu} 3} \right) \end{matrix}$

According to certain aspects disclosed herein, coils in one or more charging cells may be selectively activated to provide an optimal electromagnetic field for charging a compatible device. A charging configuration may define charging cells or charging coils selected for use in charging a discovered chargeable device and may define amplitude, relative phase shifts and polarity of charging currents to be provided to the selected charging cells or charging coils. In some instances, one or more charging coils may be assigned to each charging cell, and some charging cells may overlap other charging cells. In the latter instances, the optimal charging configuration may be selected at the charging cell level. In other instances, charging cells may be defined based on placement of a device to be charged on a surface of the charging device. In these other instances, the combination of coils activated for each charging event can vary. In some implementations, a charging device may include a driver circuit that can select one or more cells and/or one or more predefined charging cells for activation during a charging event.

FIG. 6 illustrates a first example in which a response 600 to a passive ping decays according to Equation 3. After the excitation pulse at time t=0, the voltage and/or current is seen to oscillate at the resonant frequency defined by Equation 1, and with a decay rate defined by Equation 3. The first cycle of oscillation begins at voltage level V₀ and V_(LC) continues to decay to zero as controlled by the Q factor and ω. The example illustrated in FIG. 6 represents a typical open or unloaded response when no object is present or proximate to the charging pad. In FIG. 6 the value of the Q factor is assumed to be 20.

FIG. 7 illustrates a second example in which a response 700 to a passive ping decays according to Equation 3. After the excitation pulse at time=0, the voltage and/or current is seen to oscillate at the resonant frequency defined by Equation 1, and with a decay rate defined by Equation 3. The first cycle of oscillation begins at voltage level V₀ and V_(LC) continues to decay to zero as controlled by the Q factor and w. The example illustrated in FIG. 7 represents a loaded response when an object is present or proximate to the charging pad loads the coil. In FIG. 6 the Q factor may have a value of 7. V_(LC) oscillates at a higher frequency in the response 700 with respect to the response 600.

FIG. 8 illustrates a set of examples in which differences in responses 800, 820, 840 may be observed. A passive ping is initiated when a driver circuit 504 excites the resonant circuit 506 using a pulse that is shorter than 2.5 μs. Different types of wireless receivers and foreign objects placed on the transmitter result in different responses observable in the voltage at the LC node 510 or current in the resonant circuit 506 of the transmitter. The differences may indicate variations in the Q factor of the resonant circuit 506 frequency of the oscillation of V₀. Table 2 illustrates certain examples of objects placed on the charging pad in relation to an open state.

TABLE 2 V_(peak) 50% Decay Q Object Frequency (mV) Cycles Factor None present 96.98 kHz 134 mV 4.5 20.385 Type-1 Receiver 64.39 kHz  82 mV 3.5 15.855 Type-2 Receiver 78.14 kHz  78 mV 3.5 15.855 Type-3 Receiver 76.38 kHz 122 mV 3.2 14.496 Misaligned Type-3 210.40 kHz  110 mV 2.0 9.060 Receiver Ferrous object 93.80 kHz 110 mV 2.0 9.060 Non-ferrous object 100.30 kHz  102 mV 1.5 6.795

In Table 2, the Q factor may be calculated as follows:

$\begin{matrix} {{Q = {\frac{\pi N}{\ln \; (2)} \cong {{4.5}3N}}},} & \left( {{Eq}.\mspace{14mu} 3} \right) \end{matrix}$

where N is the number of cycles from excitation until amplitude falls below 0.5 V₀.

Selectively Activating Coils

According to certain aspects disclosed herein, transmitting coils in one or more charging cells may be selectively activated to provide an optimal electromagnetic field for charging a compatible device. In some instances, transmitting coils may be assigned to charging cells, and some charging cells may overlap other charging cells. In the latter instances, the optimal charging configuration may be selected at the charging cell level. In other instances, charging cells may be defined based on placement of a device to be charged on a charging surface. In these other instances, the combination of coils activated for each charging event can vary. In some implementations, a charging device may include a driver circuit that can select one or more cells and/or one or more predefined charging cells for activation during a charging event.

FIG. 9 is a flowchart 900 that illustrates a power transfer management procedure involving multiple sensing and/or interrogation techniques that may be employed by a wireless charging device implemented in accordance with certain aspects disclosed herein. The procedure may be initiated periodically and, in some instances, may be initiated after the wireless charging device exits a low-power or sleep state. In one example, the procedure may be repeated at a frequency calculated to provide sub-second response to placement of a device on a charging pad. The procedure may be re-entered when an error condition has been detected during a first execution of the procedure, and/or after charging of a device placed on the charging pad has been completed.

At block 902, a controller may perform an initial search using capacitive proximity sensing. Capacitive proximity sensing may be performed quickly and with low power dissipation. In one example, capacitive proximity sensing may be performed iteratively, where one or more transmission coils is tested in each iteration. The number of transmission coils tested in each iteration may be determined by the number of sensing circuits available to the controller. At block 904, the controller may determine whether capacitive proximity sensing has detected the presence or potential presence of an object proximate to one of the transmission coils. If no object is detected by capacitive proximity sensing, the controller may cause the charging device to enter a low-power, idle and/or sleep state at block 924. If an object has been detected, the controller may initiate passive ping sensing at block 906.

At block 906, the controller may initiate passive ping sensing to either detect (in the case where capacitive sensing is not used) or to confirm the presence of (in the case where capacitive sensing is not used) an object near one or more (N) transmission coils, and/or to evaluate the nature of the proximately located object. Passive ping sensing may consume a similar quantity of power but span a greater of time than capacitive proximity sensing. In one example, each passive ping can be completed in approximately 100 μs and may expend 0.25 μJ. A passive ping may be provided to each transmission coil identified as being of interest by capacitive proximity sensing. In some implementations, a passive ping may be provided to a grouping of transmission coils located near each transmission coil identified as being of-interest by capacitive proximity sensing, and the grouping may include overlaid transmission coils. At block 908, the controller may determine whether passive ping sensing has detected the presence of a potentially chargeable device proximate to one of the transmission coils where the potentially chargeable device may include a receiving coil. If a potentially chargeable device has been detected, the controller may initiate active digital ping sensing at block 910. If no potential chargeable device has been detected, passive ping sensing may continue at block 906 until all of the coils have been tested and/or the controller terminates passive ping sensing. If no potential chargeable device has been detected, passive ping sensing may continue at block 1306 to test a next coil in the N number of coils. Passive ping sensing continues until all N coils are tested as illustrated by decision block 1308. In one example, the controller terminates passive ping sensing after all transmitting coils have been tested. When passive ping sensing fails to find a potentially chargeable device, the controller may cause the charging device to enter a low-power, idle and/or sleep state. In some implementations, passive ping sensing may be paused when a potentially chargeable device is detected so that an active ping can be used to interrogate the potentially chargeable device. Passive ping sensing may be resumed after the results of an active ping have been obtained.

At block 910, the controller may use an active ping to interrogate a potentially chargeable device. The active ping may be provided to a transmitting coil identified by passive ping sensing. In one example, a standards-defined active ping exchange can be completed in approximately 90 ms and may expend 80 mJ. An active ping may be provided to each transmission coil associated with a potentially chargeable device.

At block 912, the controller may further identify and configure a chargeable device. The active ping provided at block 910 may be configured to stimulate a chargeable device such that it transmits a response that includes information identifying the chargeable device. In some instances, the controller may fail to identify or configure a potentially chargeable device detected by passive ping, and the controller may resume a search based on passive ping at block 906. At block 914, the controller may determine whether a baseline charging profile or negotiated charging profile should be used to charge an identified chargeable device. The baseline, or default charging profile may be defined by standards. In one example, the baseline profile limits charging power to 5 W. In another example, a negotiated charging profile may enable charging to proceed at up to 15 W. When a baseline charging profile is selected, the controller may begin transferring power (charging) at block 920.

At block 916, the controller may initiate a standards-defined negotiation and calibration process that can optimize power transfer. The controller may negotiate with the chargeable device to determine an extended power profile that is different from a power profile defined for the baseline charging profile. The controller may determine at block 918 that the negotiation and calibration process has failed and may terminate the power transfer management procedure. When the controller determines at block 918 that the negotiation and calibration process has succeeded, charging in accordance with the negotiate profile may commence at block 920.

At block 922, the controller may determine whether charging has been successfully completed. In some instances, an error may be detected when a negotiated profile is used to control power transfer. In the latter instance, the controller may attempt to renegotiate and/or reconfigure the profile at block 916. The controller may terminate the power transfer management procedure when charging has been successfully completed.

In some examples, the initial search using capacitive proximity sensing or the passive ping sensing may be bypassed or omitted from the power transfer management procedure illustrated in FIG. 9. In some examples, other sensing techniques may be used to sense the presence of an object or chargeable device. Other techniques may involve the use of sensors, for example.

According to certain aspects disclosed herein, coils in one or more charging cells may be selectively activated to provide an optimal electromagnetic field for charging a compatible device. In some instances, coils may be assigned to charging cells, and some charging cells may overlap other charging cells. In the latter instances, the optimal charging configuration may be selected at the charging cell level. In other instances, charging cells may be defined based on placement of a device to be charged on a charging surface of a wireless charging device. In these other instances, the combination of coils activated for each charging event can vary. In some implementations, a charging device may include a driver circuit that can select one or more cells and/or one or more predefined charging cells for activation during a charging event.

FIG. 10 illustrates a topology 1000 in which each coil or charging cell is individually and/or directly driven by a driver circuit 1002 in accordance with certain aspects disclosed herein. The driver circuit 1002 may be configured to select one or more coils or charging cells 100 from a group of coils 1004 to charge a receiving device. It will be appreciated that the concepts disclosed here in relation to charging cells 100 may be applied to selective activation of individual coils or stacks of coils. Charging cells 100 that are not in use receive no current flow. A relatively large number of charging cells 100 may be in use and a switching matrix may be employed to drive individual coils or groups of coils. In one example, a first switching matrix may configure connections that define a charging cell or group of coils to be used during a charging event and a second switching matrix (see, e.g., FIG. 15) may be used to activate the charging cell and/or group of selected coils. The availability of direct drive to one or more coils may permit the charging device to concurrently transmit a ping through different groupings of coils.

FIG. 11 illustrates possible configurations 1100, 1120, 1130, 1140 of a charging surface and chargeable device 1102 that may determine the combination of charging coils activated for a charging event. In the illustrated example, the chargeable device 1102 has an area that is of similar magnitude to charging coils (or charging cells) of a charging surface. In the first and second configurations 1100, 1120, the chargeable device 1102 is larger than a single charging coil 1104. Based on the geometry and arrangement of the charging coils 1104, 1106, 1108, 1110 the chargeable device 1102 can physically cover adjacent charging coils. In the third configuration 1130 and fourth configuration 1140, for example, the chargeable device 1102 has been placed such that it substantially overlaps a single charging coil 1108 and partially covers multiple other charging coils 1104, 1106, 1110. When the chargeable device 1102 has established its presence over a charging coil 1108 and is receiving power from the charging coil 1108, the adjacent charging coils 1104, 1106, 1110 may be unusable for charging other devices due to the interference in electromagnetic flux. In some instances, configuration information transmitted to a first charging cell by a first chargeable device through modulation of the electromagnetic flux may be received by a second charging cell and misinterpreted as configuration information for a second chargeable device. In the latter example, inefficient power transfer may occur when the second chargeable device is incapable of handling power levels requested by the first chargeable device.

Certain aspects of this disclosure can prevent adjacent charging coils 1104, 1106, 1110 from interfering with the chargeable device 1102 during charging. In some examples, the adjacent charging coils 1104, 1106, 1110 may be marked or considered unusable for charging other devices. In some examples, the adjacent charging coils 1104, 1106, 1110 may be blocked from participating in device discovery procedures. In one example, the adjacent charging coils 1104, 1106, 1110 may be excluded from differential capacitive sensing, passive ping and/or active ping procedures. In another example, negative results may be preconfigured for the adjacent charging coils 1104, 1106, 1110 when initiating differential capacitive sensing, passive ping and/or active ping procedures. Result pre-configuration and/or blocking of adjacent charging coils 1104, 1106, 1110 from discovery procedures can prevent the inclusion of the adjacent charging coils 1104, 1106, 1110 in active charging cells of a charging configuration.

In one aspect of the disclosure, the adjacent charging coils 1104, 1106, 1110 can be excluded from an active ping discovery procedure. During active ping discovery, the charging system may ping or scan all coils in a predefined, preconfigured parallel, sequential, pseudorandom or random sequence in an attempt to detect a chargeable device 1102. In an initial configuration 1130, all charging coils in the charging surface may be available to be used for charging. In the fourth configuration 1140, presence of the chargeable device 1102 has been established and the chargeable device 1102 is being charged by an optimally positioned charging coil 1108. In the fourth configuration 1140, the unusable adjacent charging coils 1104, 1106, 1110 are blocked until the optimally positioned charging coil 1108 has been released from its charging contract with the chargeable device 1102.

In accordance with certain aspects of this disclosure, any number of charging coils can be blocked around the chargeable device. FIG. 12 illustrates configurations 1200, 1220 of a chargeable device 1202, 1222 on a surface of a wireless charging device in which certain coils are unusable or blocked for discovery purposes when the chargeable device 1202, 1222 is being charged. The number and location of unusable charging coils may be defined by a charging configuration for the chargeable device 1202, 1222 and may vary based on the type of a charging coil 1210, 1228 that is optimally positioned or selected for charging the chargeable device 1202, 1222, the charging contract or configuration negotiated between the wireless charging device and the chargeable device 1202, 1222, and the topology or configuration of the surface of the wireless charging device. In the first configuration 1200, two concentric rings of charging coils 1206, 1208 adjacent to an active charging coil 1210 are blocked or disabled. A concentric ring of charging coils may include charging coils that are on or within a circle that is concentric with the active charging coil 1210. The number of blocked or disabled concentric rings of charging coils 1204 may be selected based on the maximum charging power, configured charging power or contracted charging power that may be transmitted through the active charging coil 1210 or potentially through another charging coil 1204, or for other reasons. For example, a larger number of concentric rings of charging coils may be blocked when the wireless charging device has many smaller charging coils than when the wireless charging device has fewer larger coils.

In the second configuration 1220, the wireless charging device employs sensing techniques that can detect the edges of the chargeable device 1222 on a charging surface. In another example, the outline of the chargeable device 1222 can be detected using capacitive sense, inductive sense, pressure, Q-factor measurement or any other suitable device locating technology. In the illustrated example, the chargeable device 1222 has an elongated shape and the number of concentric circles of blocked charging coils may be selected based on inefficient tradeoffs when edge detection is unavailable or unused. For example, tradeoffs may be made to provide adequate protection for larger devices, devices with asymmetric outlines and smaller devices. In accordance with certain aspects of the disclosure, edge detection can enable blocking of charging coils 1226 adjacent to the outline or footprint of the chargeable device 1222 when the active coil 1228 is located substantially in the center of the outline of the chargeable device 1222. The footprint of the chargeable device 1222 may refer to the projected coverage of the charging surface by the chargeable device 1222, while the outline of the chargeable device 1222 may be defined by physical edges of the chargeable device 1222 when laid flat on the charging surface. Charging coils 1224, 1230 immediately adjacent to the chargeable device 1222 can be blocked regardless of distance from the active coil 1228. In the latter example, the use of edge sensing techniques can protect the chargeable device 1222 from interference when the chargeable device 1222 has an asymmetric outline that may not be optimally protected by locking a fixed number of concentric rings of adjacent charging coils.

In certain implementations, a chargeable device may receive power from two or more active coils. In one example, the chargeable device may have a relatively large footprint with respect to the charging surface and may have multiple receiving coils that can engage multiple charging coils to receive power. In another example, a receiving coil of the chargeable device may be placed substantially equidistant from two or more charging coils and a charging configuration may be defined whereby two or more adjacent charging coils in the charging surface provide power to the chargeable device. In these examples, an exclusion zone may be defined around the active coils such that charging coils within or impinging on the exclusion zone device can be blocked.

The use of restricted device discovery and charging activity blocking on adjacent charging coils or charging coils that are known to be under a chargeable device 1102, 1202, 1222 can reduce power draw since only the charging coils that are outside the footprint of a chargeable device can use and/or dissipate power during charging and/or discovery. A reduced electromagnetic signature may be obtained. For example, electromagnetic radiation can be reduced when fewer charging coils are involved in device discovery. In some instances, the reduction in electromagnetic signature can enable the charging device to more easily satisfy regulatory standards such as Federal Communications Commission (FCC) and Conformité Européenne (European Conformity or CE) standards.

FIG. 13 is flowchart 1300 illustrating one example of a method for operating a charging device. The method may be performed by a controller provided in a wireless charging apparatus. At block 1302, the controller may determine that a chargeable device is positioned proximate to a charging coil provided by a charging surface. At block 1304, the controller may provide a charging current to the charging coil. At block 1306, the controller may exclude a plurality of adjacent coils from operation while the current is provided to the charging coil. Each of the adjacent coils may be located within the charging surface neighboring to the charging coil.

In some implementations, the controller may exclude the plurality of adjacent coils from participating in one or more types of device discovery procedures. The one or more types of device discovery procedures may include a discovery procedure involving differential capacitive sense. The one or more types of device discovery procedures may include a passive ping discovery procedure. The one or more device types of discovery procedures may include an active ping discovery procedure.

The controller may exclude the plurality of adjacent coils from operation by refraining from providing charging current to the plurality of adjacent coils while the current is provided to the charging coil. The controller may exclude the plurality of adjacent coils from operation by blocking wireless communication through the plurality of adjacent coils while the current is provided to the charging coil. The plurality of adjacent coils include coils may be located on or within a circle that is concentric with the charging coil. The plurality of adjacent coils may be arranged around a footprint of the chargeable device on the charging surface.

In some instances, the controller may determine that the chargeable device is positioned proximate to the charging coil by detecting the chargeable device during a device discovery procedure that includes differential capacitive sense, passive ping or active ping.

Example of a Processing Circuit

FIG. 14 is a diagram illustrating an example of a hardware implementation for an apparatus 1400 that may be incorporated in a charging device or in a receiving device that enables a battery to be wirelessly charged. In some examples, the apparatus 1400 may perform one or more functions disclosed herein. In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements as disclosed herein may be implemented using a processing circuit 1402. The processing circuit 1402 may include one or more processors 1404 that are controlled by some combination of hardware and software modules. Examples of processors 1404 include microprocessors, microcontrollers, digital signal processors (DSPs), SoCs, ASICs, field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, sequencers, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. The one or more processors 1404 may include specialized processors that perform specific functions, and that may be configured, augmented or controlled by one of the software modules 1416. The one or more processors 1404 may be configured through a combination of software modules 1416 loaded during initialization, and further configured by loading or unloading one or more software modules 1416 during operation.

In the illustrated example, the processing circuit 1402 may be implemented with a bus architecture, represented generally by the bus 1410. The bus 1410 may include any number of interconnecting buses and bridges depending on the specific application of the processing circuit 1402 and the overall design constraints. The bus 1410 links together various circuits including the one or more processors 1404, and storage 1406. Storage 1406 may include memory devices and mass storage devices and may be referred to herein as computer-readable media and/or processor-readable media. The storage 1406 may include transitory storage media and/or non-transitory storage media.

The bus 1410 may also link various other circuits such as timing sources, timers, peripherals, voltage regulators, and power management circuits. A bus interface 1408 may provide an interface between the bus 1410 and one or more transceivers 1412. In one example, a transceiver 1412 may be provided to enable the apparatus 1400 to communicate with a charging or receiving device in accordance with a standards-defined protocol. Depending upon the nature of the apparatus 1400, a user interface 1418 (e.g., keypad, display, speaker, microphone, joystick) may also be provided, and may be communicatively coupled to the bus 1410 directly or through the bus interface 1408.

A processor 1404 may be responsible for managing the bus 1410 and for general processing that may include the execution of software stored in a computer-readable medium that may include the storage 1406. In this respect, the processing circuit 1402, including the processor 1404, may be used to implement any of the methods, functions and techniques disclosed herein. The storage 1406 may be used for storing data that is manipulated by the processor 1404 when executing software, and the software may be configured to implement any one of the methods disclosed herein.

One or more processors 1404 in the processing circuit 1402 may execute software. Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, algorithms, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside in computer-readable form in the storage 1406 or in an external computer-readable medium. The external computer-readable medium and/or storage 1406 may include a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., a compact disc (CD) or a digital versatile disc (DVD)), a smart card, a flash memory device (e.g., a “flash drive,” a card, a stick, or a key drive), RAM, ROM, a programmable read-only memory (PROM), an erasable PROM (EPROM) including EEPROM, a register, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. The computer-readable medium and/or storage 1406 may also include, by way of example, a carrier wave, a transmission line, and any other suitable medium for transmitting software and/or instructions that may be accessed and read by a computer. Computer-readable medium and/or the storage 1406 may reside in the processing circuit 1402, in the processor 1404, external to the processing circuit 1402, or be distributed across multiple entities including the processing circuit 1402. The computer-readable medium and/or storage 1406 may be embodied in a computer program product. By way of example, a computer program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

The storage 1406 may maintain software maintained and/or organized in loadable code segments, modules, applications, programs, etc., which may be referred to herein as software modules 1416. Each of the software modules 1416 may include instructions and data that, when installed or loaded on the processing circuit 1402 and executed by the one or more processors 1404, contribute to a run-time image 1414 that controls the operation of the one or more processors 1404. When executed, certain instructions may cause the processing circuit 1402 to perform functions in accordance with certain methods, algorithms and processes described herein.

Some of the software modules 1416 may be loaded during initialization of the processing circuit 1402, and these software modules 1416 may configure the processing circuit 1402 to enable performance of the various functions disclosed herein. For example, some software modules 1416 may configure internal devices and/or logic circuits 1422 of the processor 1404 and may manage access to external devices such as a transceiver 1412, the bus interface 1408, the user interface 1418, timers, mathematical coprocessors, and so on. The software modules 1416 may include a control program and/or an operating system that interacts with interrupt handlers and device drivers, and that controls access to various resources provided by the processing circuit 1402. The resources may include memory, processing time, access to a transceiver 1412, the user interface 1418, and so on.

One or more processors 1404 of the processing circuit 1402 may be multifunctional, whereby some of the software modules 1416 are loaded and configured to perform different functions or different instances of the same function. The one or more processors 1404 may additionally be adapted to manage background tasks initiated in response to inputs from the user interface 1418, the transceiver 1412, and device drivers, for example. To support the performance of multiple functions, the one or more processors 1404 may be configured to provide a multitasking environment, whereby each of a plurality of functions is implemented as a set of tasks serviced by the one or more processors 1404 as needed or desired. In one example, the multitasking environment may be implemented using a timesharing program 1420 that passes control of a processor 1404 between different tasks, whereby each task returns control of the one or more processors 1404 to the timesharing program 1420 upon completion of any outstanding operations and/or in response to an input such as an interrupt. When a task has control of the one or more processors 1404, the processing circuit is effectively specialized for the purposes addressed by the function associated with the controlling task. The timesharing program 1420 may include an operating system, a main loop that transfers control on a round-robin basis, a function that allocates control of the one or more processors 1404 in accordance with a prioritization of the functions, and/or an interrupt driven main loop that responds to external events by providing control of the one or more processors 1404 to a handling function.

In one implementation, the apparatus 1400 includes or operates as a wireless charging apparatus that has a battery charging power source coupled to a charging circuit, a plurality of charging cells and a controller, which may be included in one or more processors 1404. The plurality of charging cells may be configured to provide a charging surface. At least one coil may be configured to direct an electromagnetic field through a charge transfer area of each charging cell.

The controller may be configured to manage or perform a passive ping procedure by providing a pulse to the charging circuit, detecting a frequency of oscillation of the charging circuit responsive to the pulse or a rate of decay of the oscillation of the charging circuit, and determining that a chargeable device has been placed in proximity to a coil of the charging circuit based on changes in a characteristic of the charging circuit. The pulse may have a duration that is less than half the period of a nominal resonant frequency of the charging circuit. In some instances, the pulse has a duration that is multiple periods of the nominal resonant frequency of the charging circuit. In one example, the change in the characteristic of the charging circuit causes a change in rate of decay of the oscillation of the charging circuit. In one example, the change in the characteristic of the charging circuit causes a change in the frequency of oscillation of the charging circuit to vary with respect to the resonant frequency of the charging circuit.

In certain examples, the controller is configured to determine that a chargeable device is positioned proximate to a charging coil provided by a charging surface, provide a charging current to the charging coil, and exclude a plurality of adjacent coils from operation while the current is provided to the charging coil. Each of the adjacent coils may be located within the charging surface adjacent to the charging coil.

In some implementations, the controller may exclude the plurality of adjacent coils from participating in one or more device discovery procedures. The one or more device discovery procedures may include a discovery procedure involving differential capacitive sense. The one or more device discovery procedures may include a passive ping discovery procedure. The one or more device discovery procedures may include an active ping discovery procedure.

The controller may exclude the plurality of adjacent coils from operation by refraining from providing charging current to the plurality of adjacent coils while the current is provided to the charging coil. The controller may exclude the plurality of adjacent coils from operation by blocking wireless communication through the plurality of adjacent coils while the current is provided to the charging coil. The plurality of adjacent coils include coils may be located on or within a circle that is concentric with the charging coil. The plurality of adjacent coils may be arranged around a footprint of the chargeable device on the charging surface.

In some instances, the controller may determine that the chargeable device is positioned proximate to the charging coil by detecting the chargeable device during a device discovery procedure that includes differential capacitive sense, passive ping or active ping.

In some implementations, the storage 1406 maintains instructions and information where the instructions are configured to cause the one or more processors 1404 to determine that a chargeable device is positioned proximate to a charging coil provided by a charging surface, provide a charging current to the charging coil, and exclude a plurality of adjacent coils from operation while the current is provided to the charging coil. Each of the adjacent coils may be located within the charging surface adjacent to the charging coil.

In some implementations, the instructions are configured to cause the one or more processors 1404 to exclude the plurality of adjacent coils from participating in one or more device discovery procedures. The one or more device discovery procedures may include a discovery procedure involving differential capacitive sense. The one or more device discovery procedures may include a passive ping discovery procedure. The one or more device discovery procedures may include an active ping discovery procedure.

The instructions are configured to cause the one or more processors 1404 to exclude the plurality of adjacent coils from operation by refraining from providing charging current to the plurality of adjacent coils while the current is provided to the charging coil. The controller may exclude the plurality of adjacent coils from operation by blocking wireless communication through the plurality of adjacent coils while the current is provided to the charging coil. The plurality of adjacent coils include coils may be located on or within a circle that is concentric with the charging coil. The plurality of adjacent coils may be arranged around a footprint of the chargeable device on the charging surface.

In some instances, instructions are configured to cause the one or more processors 1404 to determine that the chargeable device is positioned proximate to the charging coil by detecting the chargeable device during a device discovery procedure that includes differential capacitive sense, passive ping or active ping.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” Unless specifically stated otherwise, the term “some” refers to one or more. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.” 

What is claimed is:
 1. A method for operating a wireless charging device, comprising: determining that a chargeable device is positioned proximate to a charging coil provided at a charging surface of the wireless charging device; providing a charging current to the charging coil; and excluding a plurality of adjacent coils from operation while the current is provided to the charging coil, wherein each of the adjacent coils is located on the charging surface adjacent to the charging coil.
 2. The method of claim 1, further comprising: excluding the plurality of adjacent coils from participating in one or more device discovery procedures.
 3. The method of claim 2, wherein the one or more device discovery procedures include a discovery procedure involving differential capacitive sense.
 4. The method of claim 2, wherein the one or more device discovery procedures include a passive ping discovery procedure.
 5. The method of claim 2, wherein the one or more device discovery procedures include an active ping discovery procedure.
 6. The method of claim 1, wherein excluding the plurality of adjacent coils from operation comprises: refraining from providing charging current to the plurality of adjacent coils while the current is provided to the charging coil.
 7. The method of claim 1, wherein excluding the plurality of adjacent coils from operation comprises: blocking wireless communication through the plurality of adjacent coils while the current is provided to the charging coil.
 8. The method of claim 1, wherein the plurality of adjacent coils includes coils located on or within a circle that is concentric with the charging coil.
 9. The method of claim 1, wherein the plurality of adjacent coils is arranged around a footprint of the chargeable device on the charging surface.
 10. The method of claim 1, wherein determining that the chargeable device is positioned proximate to the charging coil comprises: detecting the chargeable device during a device discovery procedure that includes differential capacitive sense, passive ping or active ping.
 11. A processor-readable storage medium comprising code that, when executed by a processor, cause the processor to: determine that a chargeable device is positioned proximate to a charging coil provided at a charging surface of a wireless charging device; provide a charging current to the charging coil; and exclude a plurality of adjacent coils from operation while the current is provided to the charging coil, wherein each of the adjacent coils is located on the charging surface adjacent to the charging coil.
 12. The processor-readable storage medium of claim 11, further comprising code that causes the processor to: exclude the plurality of adjacent coils from participating in one or more device discovery procedures when the plurality of adjacent coils is excluded from operation.
 13. The processor-readable storage medium of claim 12, wherein the one or more device discovery procedures include a passive ping discovery procedure.
 14. The processor-readable storage medium of claim 12, wherein the one or more device discovery procedures include an active ping discovery procedure.
 15. The processor-readable storage medium of claim 11, further comprising code that causes the processor to: refrain from providing charging current to the plurality of adjacent coils while the current is provided to the charging coil and when the plurality of adjacent coils is excluded from operation.
 16. The processor-readable storage medium of claim 11, further comprising code that causes the processor to: block wireless communication through the plurality of adjacent coils while the current is provided to the charging coil when the plurality of adjacent coils is excluded from operation.
 17. A wireless charging device, comprising: a charging surface comprising a plurality of charging cells; one or more wireless transmitter circuits each configured to be selectively coupled to one or more of the plurality of charging cells; and a controller configured to: determine that a chargeable device is positioned proximate to a charging coil provided at a charging surface of the wireless charging device; provide a charging current to the charging coil; and exclude a plurality of adjacent coils from operation while the current is provided to the charging coil, wherein each of the adjacent coils is located on the charging surface adjacent to the charging coil.
 18. The wireless charging device of claim 17, wherein the controller configured to: exclude the plurality of adjacent coils from participating in one or more device discovery procedures when the plurality of adjacent coils is excluded from operation.
 19. The wireless charging device of claim 17, wherein the controller configured to: refrain from providing charging current to the plurality of adjacent coils while the current is provided to the charging coil and when the plurality of adjacent coils is excluded from operation.
 20. The wireless charging device of claim 17, wherein the controller configured to: block wireless communication through the plurality of adjacent coils while the current is provided to the charging coil when the plurality of adjacent coils is excluded from operation. 